I have one question (as newbie) why we will trust those new smart apps and why we even trust this coinb.in website as what metrices make them our first priority. To be honest I little afraid to lock my BTC for like 5 or 10 years. And I hope only inheritance related cases needed these types of functions. And I also doubt if anyone really have used these feature provided by any of the platform for inheritance purposes.
First of all this feature isn’t a must to use if you don’t want to lose control of that particular funds. It is only recommended when you wish to inherit or gift a certain amount of bitcoin to someone but don’t want it spent till your specified time or probably you yourself don’t want to spend it till that time, other than that there is no need to use the feature.
Talking about a reputable wallet to use aside the coinb.in then bitcoin core and electrum will be better, since both of the wallets have proven to be the most reliable and trustworthy ones out there.
First thing is to create an address that would recieve the transaction and keep its keys or seeds save and then initiate the transaction.
On using electrum you need to specify the block height. You look at the current block and calculate it to the date you want like maybe 3 years from now. With like 808139 block already mined you need to add to the number of blocks to be confirmed in that 3 years. It is reported that 144 blocks is mined a day with an average Time of 10 minutes (although this can vary due to the time of mining blocks which differs). So for three years now with approximately 366 days then the block need for 3 years will be 52704 blocks. 808139+52704=860843.
Set the time lock to 860843 for lock time of 3 years from now.